linux-kernel - [PATCH V2 1/3] mm/slub: pack red_left_pad with another int to save a word

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Message-Id: <20170502144533.10729-2-richard.weiyang@gmail.com>
Date:   Tue,  2 May 2017 22:45:31 +0800
From:   Wei Yang <richard.weiyang@...il.com>
To:     cl@...ux.com, penberg@...nel.org, rientjes@...gle.com,
        iamjoonsoo.kim@....com, akpm@...ux-foundation.org,
        willy@...radead.org
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Wei Yang <richard.weiyang@...il.com>
Subject: [PATCH V2 1/3] mm/slub: pack red_left_pad with another int to save a word

On 64bit arch, struct is 8-bytes aligned, so int will occupy a word if it
doesn't sits well.

This patch pack red_left_pad with reserved to save 8 bytes for struct
kmem_cache on a 64bit arch.

Signed-off-by: Wei Yang <richard.weiyang@...il.com>
---
 include/linux/slub_def.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index 07ef550c6627..ec13aab32647 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -79,9 +79,9 @@ struct kmem_cache {
 	int inuse;		/* Offset to metadata */
 	int align;		/* Alignment */
 	int reserved;		/* Reserved bytes at the end of slabs */
+	int red_left_pad;	/* Left redzone padding size */
 	const char *name;	/* Name (only for display!) */
 	struct list_head list;	/* List of slab caches */
-	int red_left_pad;	/* Left redzone padding size */
 #ifdef CONFIG_SYSFS
 	struct kobject kobj;	/* For sysfs */
 #endif
-- 
2.11.0